OBJECTIVES: 1. Develop a new enzymatic method for the synthesis of malonaldehyde that will be useful for work with a radiolabelled product. 2. Determine rate constant for reaction of glutathione peroxidase with linoleic acid hydroperoxide. 3. Study antioxidant protector systems and peroxidation reactions in vivo, with an insect as a model. 4. Monitor lipid peroxidation induced in vivo by a variety of halogenated hydrocarbons. 5. Study the involvement of lipid peroxidation in heavy metal toxicities. 6. Study the question of whether increased physiological activity induces low level lipid peroxidation in vivo, with exercising rats as a model and with pentane production as an index.